A vast number of people are affected by conditions that result in profound muscle weakness or impaired motor control that impede the ability to walk. If motor function is completely lost, rehabilitation of walking function may be delayed until the patient is able move actively. Delayed therapy often leads to secondary impairments that exacerbate a patient's functional losses such as disuse atrophy and general deconditioning. Currently, therapists can begin rehabilitation of walking by using lower extremity braces or body weight supported treadmill training to support the weak limb. No currently available lower extremity braces can provide the patient the experience of typical movement patterns; rather braces are designed to immobilze the limb on which the patient bears weight. This fosters abnormal, inefficient and very energy costly movement patterns that might be difficult to overcome. During body weight supported treadmill training the body is suspended over a treadmill and all or part of the body weight is eliminated. Typical walking patterns are simulated by a manual positioning of the limb by therapists, a very time intensive and costly form of rehabilitation. The proposed project involves the development of a Smart Knee Brace (SKB) for use in rehabilitation of walking in persons with lower extremity weakness. The purpose of this study is to develop the SKB that will help to control knee movement during the stance phase of gait by encouraging more normal movement patterns while allowing free knee motion during the swing phase, something no commercially available braces can do. The SKB will provide control of the knee joint that will be adjusted for each patient based on his or her walking ability and the goals of their rehabilitation. This proposal represented the first phase of the work to develop the SBK and its electronic controllers based on walking patterns from healthy older subjects. Feasibility of the SKB will also be tested on healthy subjects and 3atients with hemiparesis from stroke. The data collected during the proposed work will be used to plan Future clinical phases of the work.